Field of the Invention
The present invention relates to a technique to predict a compression method at a transfer destination in the case where image data is transferred between apparatuses.
Description of the Related Art
In recent years, in the field of production printing in which a large amount of printed matter is formed, the number of cases is increasing where a configuration is adopted in which a RIP controller (information processing apparatus specialized in the RIP function. Hereinafter, referred to as an “external RIP controller”) is connected externally to an image forming apparatus, such as a digital multifunction peripheral. In such a configuration, the external RIP controller is in charge of generating print image data by performing rasterization on electronic data and the image forming apparatus is in charge of receiving and printing the print image data.
FIG. 1A is a diagram explaining an outline of image processing for print image data in a production printing system including an external RIP controller and an image forming apparatus. The external RIP controller having received electronic data to be printed generates RAW image data by performing rasterization and then performs lossless compression in order to compress the image size while maintaining image quality. Then, the external RIP controller transmits RAW image data obtained by decompressing the lossless-compressed image data to the image forming apparatus at timing at which a user gives instructions to perform printing. The image forming apparatus performs lossless compression on the received RAW image data and stores the RAW image data in a primary buffer on a memory. Then, the image forming apparatus decompresses the lossless-compressed image data and performs printing.
However, normally, the amount of memory that the image forming apparatus has is smaller than the amount of memory that the external RIP controller has. Because of this, it may happen that it is not possible for the image forming apparatus to store the received RAW image data in the primary buffer.
FIG. 1B is a diagram explaining an outline of processing in the case where the RAW image data received from the external RIP controller cannot be stored in the primary buffer within the image forming apparatus. In the case where the image forming apparatus determines that it is not possible to store the RAW image data in the primary buffer even by performing compression (lossless compression), the image forming apparatus requests the external RIP controller to retransmit the same RAW image data. Upon receipt of the request, the external RIP controller transmits the same RAW image data again to the image forming apparatus. Then, the image forming apparatus applies lossy compression with a high compression ratio at this time to the RAW image data that is received again to reduce the size of the image after the compression. By doing so, it is made possible for the image forming apparatus to store the image data in the primary buffer.
By using the method in FIG. 1B, it is made possible even for the image forming apparatus having a small amount of memory to receive and store the RAW image data that is transmitted from the external RIP controller within the memory. However, with this method, the external RIP controller needs to perform processing to retransmit the same RAW image data and the image forming apparatus needs to compress the RAW image data again by using a method with a high compression ratio, and therefore, the start of printing is delayed by an amount of time corresponding to the time taken for the processing.
In relation to this point, for example, Japanese Patent Laid-Open No. 2007-013956 has disclosed a technique to predict the image data size while scanning a document with a scan apparatus at the time of storing the image data from the scan apparatus to a target apparatus. Specifically, by the scan apparatus transmitting the predicted image data size at all times to the target apparatus that is connected via a network, whether or not the image data can be stored in an empty area of the target apparatus is determined. By applying the method of Japanese Patent Laid-Open No. 2007-013956 to the above-described production printing system, it is possible to determine in advance whether the image data after compression can be stored in the target apparatus (image forming apparatus) connected via a network.
However, Japanese Patent Laid-Open No. 2007-013956 has not presented a method for dealing with the case where it is determined that the image data after compression cannot be stored in an empty area of the target apparatus, and after all, it is not possible to solve the problem of retransmission of the same image data described above.